Earth to Ground


I have been reading your comments on problems whereby the boat temperature gauge over-reads when navigation lights are put on. I have tried to find the faulty earth without success.

Can I simply bring a new earth wire from the battery to a new busbar on the dash and remake all the earth connections to the instruments (including the temp gauge) from that busbar? Is there anything I need to be careful of in doing this and should this cure the problem?

Your help would be much appreciated.


Hi Richard,

Your proposed solution will work great. The only concern would be the additional ground wire connected directly to the battery. I’m not a big fan of small and large wires connected directly to the battery. The connection is either too tight for the small terminals or too loose for the large terminals. If you are connecting directly to the battery, I would either put a zip tie or tape around all of the wires that connect each post of the battery to ensure that all positives stay segregated from the negatives. An accidental ground wire touching the positive will cause an immediate fire.

Hope this helps,


Power Distribution


Is there some sort of terminal used to send power to different parts of the boat – navigation lights, bilge pump, fishfinder, etc. from one of the boat batteries?

I know that I have to fuse them all, but what divides them?


Hi Red,

Your boat’s main power feed supplies either a marine electrical bus bar that feeds power to each individual circuit breaker or the main power lead can connect directly to the first breaker and then jumper to each additional breaker. The individual feeds or jumpers should be made from the same size wire as the panel feed.

The main power feed should have circuit protection as close as possible to the battery. The cable size should be large enough to maintain a 3% or less voltage drop to the panel feed.

Hope this helps,


Lowrance Reboots


I have a 30′ Duckworth Offshore with twin Verado’s, each having their own battery, and one house battery. The marine electrical also includes:

  • Two Lowrance HDS-8 GPS/fish finders, both powered off the boat’s house battery
  • A small 12 volt refrigerator, again powered off the house battery.

I installed a complete shore power system from your marine wiring site and it works great…with the battery charger powered by the shore power the house and engine batteries are always ready to go.

But I have a problem that for which I hope you can suggest a solution and possibly direct me to whatever hardware I might need.

My boat wiring problem:

We typically spend hours at a time deep jigging for Lake Trout. During this time, I never have the main engines or the kicker running, so there is continuous drain on the house battery from the two fish finders. If I have the fridge running, when the compressor (or whatever provides the cooling) powers on, there is a momentary large drain on the house battery that results in the two fish finders rebooting.  It’s a real pain.

Is there something that I can install between the HDS-8’s and the battery to act as a buffer to prevent the reboots? Perhaps a capacitor??? Or do I need a second house battery that just powers the HDS-8 units?

If I do have the main engines or kicker running, then they provide sufficient charging capacity to prevent the HDS-8’s from rebooting.



Hi Randall,

A very small voltage increase will prevent this from happening.

Are the HDS units powered directly to the boat battery or are they from the same distribution location as the refrigerator?

  • If they get their power from the same bus, connect them directly to the battery with circuit protection as close as possible to the battery connection.
  • If they are already directly connected, increase the wire size and check all connections for any signs of corrosion. A 1/4 of a volt is all you need to keep them from cycling.

Increase the air vent for the refrigerator. Most small refrigerators use the Danfoss compressor/controller. When they are hot, the draw 5 amps. When they are not, they draw 2.3 amps. The lower amp draw will reduce the voltage drop.

If this doesn’t work, install a larger AH (reserve capacity) house battery or simply add a second house battery.

Hope this helps,


Memory Loss

Hello Kevin,

I have a Wellcraft Portofino that I have owned for several years.

When I bought the boat it had an AM/FM CD player in the cockpit that worked fine. I added a car style radio to the salon about three years ago. I wired the unit properly and attached the “memory” lead to an empty, fused position on the same 12 volt bus as the cockpit radio.

From day one the salon radio would lose it’s memory on engine start while the cockpit radio did not. In between engines starts is not a problem. I double checked my wiring, which seemed good and wrote the problem up to buying a cheap radio on sale.

Midway through last season I replaced the cockpit AM/FM radio with a new Sony Marine unit. I now have the same problem with this radio! The tuner memory holds until I start engines. I just don’t get it!

The marine electrical is set up with two battery banks. The starboard bank is a 4-D and starts that engine and navigation equipment including the cockpit Sony radio. The port bank is a bank of four 6 volt deep cycle batteries wired series/parallel for 12 volts that start the port engine and also supplies the house.

I have checked all of the radio connections. I have switched the memory lead from the original fuse panel to different bus bars. Nothing has helped, as soon as I start an engine with the same battery bank the the AM/FM radio memory leads are attached to, the memories go blank.

I am starting to think that this is a surge problem. I believe I have confirmed this by using my master boat battery switches to start engines on the battery bank that does not have the radio memory. If I do that there is no memory loss. Starting and running my boat in this manner is not practical for me and leaves open the possibility of draining the wrong battery bank.

This situation is really starting to drive me nuts, I’d greatly appreciate any recommendations you may have.

Thank you,


Hi Mike,

Stereo memory circuits are sensitive to low voltage and you are suffering for a voltage drop “stack up” and will reset after only a few milliseconds of low voltage. This is very common with newer, higher draw, higher tech stereos.

The power feed to your helm has a drop. The more current that you draw through it, the more the voltage drop in the circuit. When higher draw devices such as bilge blowers, cockpit lights, stereos, the voltage drop is even higher. Slightly corroded connections induce voltage drops. When you start the engine, the source voltage (the battery) drops lower which makes the stereo input voltage that much lower.


  • Increase the size of the power feed wiring and ground to your helm panel.
  • Run a dedicated power and ground lead from the battery to the stereo.
  • Make sure you use circuit protection at the source of power. An increase of 0.1 volts will mean the difference between the stereo memory resetting and remaining.

Hope this helps,


Four Winns Wiring

Hello Kevin,

I have a 1989 Four Winns Liberator 201 with a 350 OMC motor. I know that it’s early, but I pulled off the boat covers today because I wanted to check everything before I put her back in the water.

When I went to hit the boat horn to test it, the horn sounded weak and eventually faded and did not work.

Next the navigation lights would not turn on. But when I hit the horn, the lights will turn on until the horn is released then they go off. Not sure if it could be a bad ground or short in the wiring.

I removed the access cover and found someone has cut and spliced wires on the boat before. There are also some wires disconnected and zip tied up and others just cut.

The boat blower motor did work when starting the boat but now it also will not turn on. I’m not an expert in marine electrical by any means but would like to find the issue my self. I have a voltmeter but never used it other than checking glow plug relays on diesel engines. I have used a test light on trailers – checking for power and such so I do have a little knowledge but not where to start on this project.

Any help would be great.



Hi Mark,

I’m a HUGE Liberator fan. I worked at Four Winns during the era after their production.

There are few marine wiring items to check since several things have quit working.

  • Main engine plug – round plug 1 1/4″ diameter on the starboard side of the engine. Unplug and check terminals
  • Boat harness ground – check ground connection on rear bell housing of the engine
  • Helm fuse block – check ground and power leads on the main fuse block under the helm

Once your find the corroded connection, replace as necessary.

Good luck,